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* GL_EXT_pixel_buffer_object test
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#include "../util/readtex.c" /* a hack, I know */
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#define IMAGE_FILE "../images/girl.rgb"
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static int ImgWidth, ImgHeight;
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static GLenum ImgFormat;
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static GLubyte *Image = NULL;
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static int APosX, APosY; /* simple drawpixels */
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static int BPosX, BPosY; /* read/draw pixels */
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static int CPosX, CPosY; /* copypixels */
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static GLboolean DrawFront = GL_FALSE;
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static GLboolean ScaleAndBias = GL_FALSE;
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static GLboolean Benchmark = GL_FALSE;
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static GLuint DrawPBO, TempPBO;
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static GLenum ReadFormat = GL_BGRA;
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static GLenum ReadType = GL_UNSIGNED_INT_8_8_8_8_REV;
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GLenum err = glGetError();
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printf("GL Error 0x%x at line %d\n", (int) err, line);
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APosX = 5; APosY = 20;
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BPosX = APosX + ImgWidth + 5; BPosY = 20;
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CPosX = BPosX + ImgWidth + 5; CPosY = 20;
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PrintString(const char *s)
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glutBitmapCharacter(GLUT_BITMAP_8_BY_13, (int) *s);
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SetupPixelTransfer(GLboolean invert)
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glPixelTransferf(GL_RED_SCALE, -1.0);
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glPixelTransferf(GL_RED_BIAS, 1.0);
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glPixelTransferf(GL_GREEN_SCALE, -1.0);
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glPixelTransferf(GL_GREEN_BIAS, 1.0);
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glPixelTransferf(GL_BLUE_SCALE, -1.0);
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glPixelTransferf(GL_BLUE_BIAS, 1.0);
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glPixelTransferf(GL_RED_SCALE, 1.0);
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glPixelTransferf(GL_RED_BIAS, 0.0);
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glPixelTransferf(GL_GREEN_SCALE, 1.0);
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glPixelTransferf(GL_GREEN_BIAS, 0.0);
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glPixelTransferf(GL_BLUE_SCALE, 1.0);
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glPixelTransferf(GL_BLUE_BIAS, 0.0);
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glClearColor(.3, .3, .3, 1);
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glClear( GL_COLOR_BUFFER_BIT );
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/** Unbind UNPACK pixel buffer before calling glBitmap */
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glBindBufferARB(GL_PIXEL_UNPACK_BUFFER_EXT, 0);
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glRasterPos2i(5, ImgHeight+25);
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PrintString("f = toggle front/back s = toggle scale/bias b = benchmark");
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glRasterPos2i(5, ImgHeight+40);
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PrintString("GL_EXT_pixel_buffer_object test");
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/* draw original image */
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glRasterPos2i(APosX, 5);
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PrintString("Original");
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glRasterPos2i(APosX, APosY);
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SetupPixelTransfer(GL_FALSE);
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/*** Draw from the DrawPBO */
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glBindBufferARB(GL_PIXEL_UNPACK_BUFFER_EXT, DrawPBO);
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glDrawPixels(ImgWidth, ImgHeight, ImgFormat, GL_UNSIGNED_BYTE, 0);
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glBindBufferARB(GL_PIXEL_UNPACK_BUFFER_EXT, 0);
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CheckError(__LINE__);
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/* do readpixels, drawpixels */
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glRasterPos2i(BPosX, 5);
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PrintString("Read/DrawPixels");
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SetupPixelTransfer(ScaleAndBias);
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/*** read into the Temp PBO */
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glBindBufferARB(GL_PIXEL_PACK_BUFFER_EXT, TempPBO);
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CheckError(__LINE__);
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GLint startTime = glutGet(GLUT_ELAPSED_TIME);
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GLdouble seconds, pixelsPerSecond;
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printf("Benchmarking...\n");
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glReadPixels(APosX, APosY, ImgWidth, ImgHeight,
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ReadFormat, ReadType, 0);
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endTime = glutGet(GLUT_ELAPSED_TIME);
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} while (endTime - startTime < 4000); /* 4 seconds */
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seconds = (double) (endTime - startTime) / 1000.0;
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pixelsPerSecond = reads * ImgWidth * ImgHeight / seconds;
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printf("Result: %d reads in %f seconds = %f pixels/sec\n",
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reads, seconds, pixelsPerSecond);
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Benchmark = GL_FALSE;
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glReadPixels(APosX, APosY, ImgWidth, ImgHeight,
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ReadFormat, ReadType, 0);
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CheckError(__LINE__);
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glRasterPos2i(BPosX, BPosY);
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glDisable(GL_DITHER);
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SetupPixelTransfer(GL_FALSE);
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CheckError(__LINE__);
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/*** draw from the Temp PBO */
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glBindBufferARB(GL_PIXEL_UNPACK_BUFFER_EXT, TempPBO);
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glDrawPixels(ImgWidth, ImgHeight, ReadFormat, ReadType, 0);
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glBindBufferARB(GL_PIXEL_UNPACK_BUFFER_EXT, 0);
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CheckError(__LINE__);
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glRasterPos2i(CPosX, 5);
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PrintString("CopyPixels");
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glRasterPos2i(CPosX, CPosY);
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glDisable(GL_DITHER);
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SetupPixelTransfer(ScaleAndBias);
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glCopyPixels(APosX, APosY, ImgWidth, ImgHeight, GL_COLOR);
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CheckError(__LINE__);
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Reshape( int width, int height )
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glViewport( 0, 0, width, height );
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glMatrixMode( GL_PROJECTION );
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glOrtho( 0.0, width, 0.0, height, -1.0, 1.0 );
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glMatrixMode( GL_MODELVIEW );
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Key( unsigned char key, int x, int y )
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ScaleAndBias = !ScaleAndBias;
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DrawFront = !DrawFront;
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glDrawBuffer(GL_FRONT);
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glReadBuffer(GL_FRONT);
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glDrawBuffer(GL_BACK);
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glReadBuffer(GL_BACK);
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printf("glDrawBuffer(%s)\n", DrawFront ? "GL_FRONT" : "GL_BACK");
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printf("GL_VERSION = %s\n", (char *) glGetString(GL_VERSION));
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printf("GL_RENDERER = %s\n", (char *) glGetString(GL_RENDERER));
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if (!glutExtensionSupported("GL_EXT_pixel_buffer_object")) {
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printf("Sorry, this demo requires GL_EXT_pixel_buffer_object\n");
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Image = LoadRGBImage( IMAGE_FILE, &ImgWidth, &ImgHeight, &ImgFormat );
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printf("Couldn't read %s\n", IMAGE_FILE);
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printf("Loaded %d by %d image\n", ImgWidth, ImgHeight );
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if (ImgFormat == GL_RGB) {
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/* convert to RGBA */
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GLubyte *image2 = (GLubyte *) malloc(ImgWidth * ImgHeight * 4);
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printf("Converting RGB image to RGBA\n");
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for (i = 0; i < ImgWidth * ImgHeight; i++) {
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image2[i*4+0] = Image[i*3+0];
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image2[i*4+1] = Image[i*3+1];
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image2[i*4+2] = Image[i*3+2];
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glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
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glPixelStorei(GL_UNPACK_ROW_LENGTH, ImgWidth);
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glPixelStorei(GL_PACK_ALIGNMENT, 1);
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glPixelStorei(GL_PACK_ROW_LENGTH, ImgWidth);
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/* put image into DrawPBO */
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glGenBuffersARB(1, &DrawPBO);
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glBindBufferARB(GL_PIXEL_UNPACK_BUFFER_EXT, DrawPBO);
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glBufferDataARB(GL_PIXEL_UNPACK_BUFFER_EXT,
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ImgWidth * ImgHeight * 4, Image, GL_STATIC_DRAW);
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/* Setup TempPBO - used for glReadPixels & glDrawPixels */
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glGenBuffersARB(1, &TempPBO);
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glBindBufferARB(GL_PIXEL_PACK_BUFFER_EXT, TempPBO);
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glBufferDataARB(GL_PIXEL_PACK_BUFFER_EXT,
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ImgWidth * ImgHeight * 4, NULL, GL_DYNAMIC_COPY);
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main( int argc, char *argv[] )
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glutInit( &argc, argv );
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glutInitWindowPosition( 0, 0 );
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glutInitWindowSize( 750, 250 );
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glutInitDisplayMode( GLUT_RGB | GLUT_DOUBLE );
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glutCreateWindow(argv[0]);
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glutReshapeFunc( Reshape );
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glutKeyboardFunc( Key );
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glutDisplayFunc( Display );